Petroni Katia, Falasca Giuseppina, Calvenzani Valentina, Allegra Domenico, Stolfi Carmine, Fabrizi Luana, Altamura Maria Maddalena, Tonelli Chiara
Dipartimento di Scienze Biomolecolari e Biotecnologie, Università degli Studi di Milano, Via Celoria 26, I-20133 Milano, Italy.
J Exp Bot. 2008;59(6):1201-13. doi: 10.1093/jxb/ern027. Epub 2008 Mar 20.
In plants, MYB transcription factors play important roles in many developmental processes including cell cycle progression, cell differentiation, and lateral organ polarity. It is shown here that the R2R3-MYB AtMYB11 gene is expressed in root and shoot meristems and also in young still meristematic leaf and flower primordia of Arabidopsis. Knock-out atmyb11-I mutants and RNAi plants germinate faster, show a faster hypocotyl and primary root elongation, develop more lateral and adventitious roots, show faster development of the inflorescence, and initiate more lateral inflorescences and fruits than wild-type plants. The opposite phenotype was displayed by plants overexpressing AtMYB11. De novo formation of root meristemoids and, consequently, macroscopic roots, from thin cell layers cultured in vitro was enhanced in explants from atmyb11-I and reduced in those from lines overexpressing AtMYB11. These findings indicate that AtMYB11 modulates overall growth in plants by reducing the proliferation activity of meristematic cells and delaying plant development.
在植物中，MYB转录因子在许多发育过程中发挥重要作用，包括细胞周期进程、细胞分化和侧生器官极性。本文表明，R2R3-MYB AtMYB11基因在拟南芥的根和茎分生组织中表达，也在幼嫩的仍具分生能力的叶片和花原基中表达。与野生型植物相比，敲除atmyb11-I突变体和RNA干扰植株发芽更快，下胚轴和主根伸长更快，发育出更多的侧根和不定根，花序发育更快，产生更多的侧生花序和果实。过表达AtMYB11的植株则表现出相反的表型。在体外培养的薄细胞层中，atmyb11-I外植体中根分生细胞团的从头形成以及由此产生的宏观根的形成增强，而过表达AtMYB11的株系中则减少。这些发现表明，AtMYB11通过降低分生细胞的增殖活性和延迟植物发育来调节植物的整体生长。
